1. In a large bowl, whisk together ginger (and accumulated juice), vinegar, lemon zest and juice, onion, cumin, cilantro, mint, salt and pepper. Whisking constantly, drizzle in vegetable oil.
2. Place shredding attachment in a food processor. Peel carrots and beets and shred. (If you don't have a food processor, shred vegetables with a box grater.)
3. Add carrots and beets to bowl with dressing and toss well. Sprinkle with scallions and serve.